Research activities on yeast will proceed along several genetic and biochemical lines. (1) Saturation and ordering of new and existing mutants on the yeast mitochondrial genome. (2) Characterization of conditional and non-conditional mutants with respect to inner mitochondrial enzymes affected and subunits altered, the latter by exploiting newly developed two dimensional gels. (3) Study the order of assembly of yeast mitochondrial inner membrane enzyme by making use of double conditional mutants in temperature shift experiments. (4) Locate genetic markers on the 4 x 10 to the 6th power dalton, circular yeast episome. (5) Study the regulation of maltase synthesis in vivo and in vitro. The in vitro studies will develop along standard lines which will involve isolation and purification of poly A terminated maltase mRNA, translation in wheat germ system, immunoprecipitation of the maltase and finally a study of the regulation of maltase mRNA synthesis. (6) Mutants in the glycolysis pathway in yeast that have already been isolated will be characterized more fully; this will include a study of nature of the mutation (structural or regulatory) and to study the extent of the glucose induced repression in such mutants. BIBLIGRAPHIC REFERENCES: J. Leff and K.-B. Lam. Bromodeoxyuridine 5'-Monophosphate Incorporation into Yeast Nuclear and Mitochondrial Deoxyribonucleic Acid. J. Bacteriol. 127, 354 (1976). K.-B. Lam and J. Marmur. Isolation and Characterization of Glycolytic Pathway Mutants of Saccharomyces cerevisiae. J. Bacteriol. (1977). In press.